Rotary hook for lock-stitch sewing machines



March 14, 1944. c. F. RUBEL 2,344,110

\ ROTARY HOOK FOR LOCK-STITCH SEWING MACHINES Filed May 17, 1940 WITNESSES:

I'NVENTORJL ATTORNEYS.

Patented Mar. 14, 1944 2,344,110 no ranr HOOK FOR LOCK-STITCH snwmo monmns Glisarles F. Rube], Chicago, 111., assignor to Union pecial Machin notation of Illinois e Company Chicago, m, a cor- Application May 17, 1940, Serial No. ssasss 6Clain1s.

This invention relates to rotary hooks useful in connection with lock stitch sewing machines. Ordinarily such hooks comprise an axially hollow cup-like rotating or hook carrying component; an axially hollow non-rotating component or bobbin case holder which fits into the rotary component and which has a circumferential rib in engagement with an internal groove or raceway in said rotating component; and a bobbin case which in turn fits into the bobbin case holder and which has a sliding latch or keeper that looks with the outer end of an axial bobbin or spool mounting stud within the bobbin case holder. Heretofore the practice has been to construct the bobbin case holder and the bobbin case throughout from steel. These parts were accordingly relatively heavy, and since their combined weight is supported by the rotating or hook carrying component, the rib of the bobbin case holder bore with correspondingly heavy pressure upon the surface of the groove in said rotating component. Under the action of, the friction and heat created by such pressure, rapid wear took place between the contacting rib and groove surfaces, particularly when the sewing machines were operatedat high speeds, which entailed frequent hook replacements at considerable expense.

My invention is directed toward overcoming the above drawbacks, that is to say, it has for-its chief aim to reduce friction and heating in rotary hooks to a minimum, not only to the end that the useful life of the hooks may be increased, but that the sewing machines may be operated at higher speeds than ordinarily. This desiratum, I a tain in practice as hereinafter more fully set forth, by constructing the bodies of the bobbin case holder and the bobbin case of the rotaiy hocks from a light weight material, such as aluminum or an alloy thereof, which dissipates heat more readily and quickly than steel; by separately forming the circumferential rib of the bobbin case holder as well as its usual axial bobbin or spool mounting stud from steel or 'other wearresistant material or alloy; and by similarly forming the usual latch parts of said bobbin case from hard wear-resistant material.

Other objects and attendant advantages will appear from the following detailedflescription of the attached drawing, wherein Fig. 1 is a fragmentary view in horizontal section of a sewing machine having a rotary hook which is constructed in accordance with my invention, the hook being shown in plan.

Fig. 2 is a view like Fig. l, but with the hook shown in axial section.

Fig. 3 shows the non-rotating component or bobbin case holder of the hook in front elevation.

Fig. 4 shows the rear elevation of the bobbin case holder with a portion thereof broken away and in section.

Fig. 5 is a perspective view of the bobbin case of the hook.

Fig. 6 is a perspective view of the separately formed rib of the bobbin case holder; and

Fig. 7'is a perspective view of a separately formed facing member associated with the bobbin case holder.

As herein illustrated, my improved rotary hook comprises a rotating or.needle loop seizing component III which is secured to an actuating shaft II; a non-rotating component or bobbin case holder I! which fits into the frontal hollow of the rotating component and which is held against rotation by the usual form of stop or arresting finger l3; and a bobbin case H which in turn fits into the bobbin case holder; and which has a slide latch ii to lock with the groove I 8 in the outer end of the axialstud or pin I! for the bobbin I8 within said holder, said latch being operable by a pivoted finger piece l9. Insofar as their configuration and arrangement is con.- cemed, the above parts are of usual design and function in the well known manner during stitch formation.

The body of the rotating component lli'which provides the needle loop seizing beak Illa may be fashioned, as ordinarily, from steel, with the gib 20 and the thread deflecting segment 2| separately formed and removably attached by screws 12 .and 23 respectively. In accordance with my invention, however, the body 25 of the non-rotating component or bobbin case holder i2 is formed from relatively light weight material, such as aluminum oran alloy thereof capable of dissipating heat readily, while its segmental circumferential rib 26 (separately illustrated inFlg. 6) is separately formed from hard wear-resistant metal such as steel.- In order to facilitate accurate assembling, the body 25 of the bobbin case holder I2 is provided with a shallow peripheral recess 21 into which the rib is sprung and which is accurately conformative with said rib so as to engage the latter with a snug tight fit all around. For greater assurance against subsequent lateral and circumferential shifting on the body 25 of the bobbin case holder, the rib 26 is finally fixed in position by rivets 28 passed through preallocated registering holes 29 and 3|! in the two parts, see Fig. 4. As a consequence of this snug tight fit, the

' heat generated in the rib by friction during high 2 speed operation of the hook is effectively transmitted to the body 25 of the bobbin case holder II for rapid dissipation therefrom, with avoidance at the same time of crevices in which lint might collect and interfere with the free transfer of heat from said rib to said body. As ordinarily, the rib 28 is adapted to engage the internal circumferential groove or raceway 3| of the rotating component In. For the purpose of offsetting wear of the needle thread clearing notch 32 at the top of the face flange 33 of the component l2 into which the stop lug 34 of the usual fixed rotation restraining finger I! of the sewing machine extends, I have provided said notch at opposite sides with steel cheek pieces 35 whereof one is separately illustrated in Fig. '7. As shown, a rivet stud 36 is anchored in each of the cheek pieces 35, and,, after being passed through prcailocated transverse holes 31 in the component I2 at the sides of the notch 32, are peened or riveted over at their outer ends to permanently secure saidpieces. The internal lug 38 at the top of the component l2 which engages the notch 39 at the top of the bobbin case M is formed, as ordinarily, as a separate piece from steel, and secured by a rivet 40. The axial stud II for the thread bobbin I8 is preferably formed from steel and appropriately anchored in the central boss ll of the bobbin case holder l2.

Also, in accordance with my invention, the body bobbin case II is fashioned from light weight heat-dissipating material like the holder l2, but the bobbin thread tensioning finger 42 and the parts i5 and I! of the latch means are preferably made from steel.

By constructing the bodies of the bobbin case holder and bobbin case (of which the combined weight is supported by the rotating component II) from light material, it will be seen that I have very considerably reduced the weight of these parts and correspondingly lessened the frictional pressure of the rib of the bobbin case holder on the surface of the internal groove or raceway in the rotating component of the hook. As a consequence, the sewing machine in which my improved hook is \used can be run at higher speeds than ordinarily without attendant overheating or excessive wear of the hook. Another advantage resulting from my invention is that, due to the lightness of the bobbin case holder and bobbin case, the needle thread loop will pass with greater ease around the bottom of said holder and its front leg around the lug ll of the detaining finger l3 during stitch formation, so that the likelihood of thread rupture is correspondingly reduced.

While I have herein, by the way of example, mentioned aluminum as a suitable material for the bodies of the bobbin case holder and bobbin case, my invention is not to be construed as limited in this respect since other materials, not necessarily metallic, may be substituted if desired, if they possess the requisite physical characteristics.

Having thus described my invention, I claim: 1. A rotary hook for lockstitch sewing machines, comprising two relatively rotating components, one of which supports the weight of the other, one component having an annular bearing groove with walls of hard wear-resistant material, and the other component having an annular rib of like material frictionally engaging the bearing groove of the first component and a separately formed body of a different material capable of more rapidly absorbing and dissipating light than the material of the groove walls and r 2. A rotary hook according to claim 1, in which the material of the body of the second component in addition to its capacity for rapid heat dissipation has the characteristic of being lighter in weight than the material of the rib.

3. A rotary hook for lockstitch sewing machines comprising two relatively rotating components one of which supports the weight of the other, one component having an annular bearing groove with walls of hard wear-resistant material, and the other component having an annular rib of like material, and a body of a different material capable of more rapidly absorbing and dissipating heat than the material of the groove walls, said rib being in the form of a split ring sprung with a snug tight fit all around into an accurately conformative peripheral receiving recess in said body, and fixed by supplemental securing means against the possibility of subsequent circumferential displacement on said body.

4. A rotary hook component for lockstitch sewing machines having a cylindric body; and a split annular bearing rib of a different material sprung with a snug tight fit all around into an accurately conformative peripheral receiving recess in said body and fixed by supplemental securing means against the possibility of subsequent relative circumferential displaceinent."

5. A rotary hook component according to claim 4, in which the rib is of hard wear-resistant material, and the body is of a material capable of rapidly absorbing and dissipating frictional heat communicated thereto from the rib.

6. A rotary hook for lockstitch sewing machines comprising an axially hollow annular rotating component with an extremal-needle loopseizing beak and an internal circumferential groove with walls of hard wear-resistant material; a hollow cylindric non-rotating component or bobbin case holder within the first component having an annular rib of hard wear-resistant material for frictionally engaging the bearing groove of the rotating component, and a separately formed body of diiferent material capable of more rapidly absorbing heat than the material of the groove walls and the rib; and a bobbin case component fitting into the holder component and likewise formed from rapid heating absorbing and dissipating material.

CHARLES I". RUBEL. 

